Conventionally, a vehicle-mounted HC measurement device described in JP Published Patent Application No. 2004-117259 A (Patent Document 1) is available as an exhaust gas analyzer for car or the like. This vehicle-mounted HC measurement device is adapted to allow a NDIR (non-dispersive infrared spectroscopy) gas analyzer, an exhaust gas flowmeter and an arithmetic operation circuit to be installed in a vehicle, the NDIR for continuously measuring the HC (hydrocarbon) concentration in exhaust gas flowing through an exhaust tube connected with an engine, the exhaust gas flowmeter continuously measuring a flow rate of the exhaust gas flowing through the exhaust tube, and the arithmetic operation circuit performing arithmetic operation of an output from the NDIR gas analyzer and an output from the exhaust gas flowmeter to continuously calculate the THC (total hydrocarbon) amount in the exhaust gas.    Patent Document 1: JP Published Patent Application No. 2004-117259 A